The relationship between abstinence, contraception, sex and teens is nothing if not complicated. On Tuesday, it got even more tangled as Utah lawmakers gave a nod to what could become the nation’s most restrictive sex-education policy if it passes: no talk of contraception and no mention of homosexuality. No mention of much, in fact, besides an emphasis on abstinence before marriage, if that.

Then on Thursday, the Guttmacher Institute, which conducts reproductive health research, came out with a study that suggests censoring sex ed won’t actually lead to teens safeguarding their virginity until they slip on a wedding ring. But sex ed classes, even the really G-rated ones, get teens to wait longer before they start having sex.

Sex ed leads teens and young adults to delay sexual intercourse, according to the research, which relied on data from the National Center for Health Statistics on about 4,691 women and men between the ages of 15 and 24. “There is an incorrect belief that talking to teens about sex promotes sex,” says study author Laura Lindberg, a senior research associate at Guttmacher.

Among those who hadn’t received sex-ed instruction before first sex, 86% of girls and 88% of boys had intercourse before they turned 20. Compare that to 78% of boys and 77% of girls who’d received sex ed. The difference may not be huge but it is significant, especially considering that the national average age of first sex is about 17 or so. These kids aren’t yet voting or legally drinking, but they are potentially making babies. “It’s not just the delay in first sex that’s important,” says Lindberg. “It’s that being older at first sex in and of itself is related to more positive sexual behaviors such as being more likely to use birth control and less likely to get pregnant. The fact that sex ed can delay sex a little still has big influences down the road.”

According to the study, 24% of boys didn’t receive any sex education before their first time having sex; ditto for 16% of girls. The percentages broke along racial lines: 34% of black males and 32% of Hispanic males hadn’t received sex ed before first sex, compared with 19% of white males. And 19% of black girls, 23% of Hispanic girls and 13% of white girls hadn’t received sex ed.

Why should we care? Because getting sex ed in school is not only associated with delaying first sex; it’s also linked to improved contraceptive use and choosing a partner closer to your age (research has shown that having a substantially younger or older partner is related to riskier outcomes).

Comprehensive sexual education should be medically accurate and provide information about delaying sex, using contraception during sex and making good decisions about partners. Yet there’s very little standardization when it comes to sexual education. Each state has its own rules, and those rules are often implemented differently within individual districts and schools. Lindberg offers up an example that’s probably far too common: “My son’s school claimed it taught about sex ed in seventh grade, but it turns out it was a one-hour lecture, and the teacher called in sick that day.”